The great majority of sets for the administration of parenteral solution, blood, plasma, or the like, in medical use contains an ester-type plasticizer to soften the vinyl. While this plastic material has many advantages for use in sets of this type, as well as non-medical devices involving plastic tubing, it has suffered a drawback that has made it undesirable to steam sterilize the plastic set. The reason for this is that polyvinyl chloride plastic generally can undergo dimensional distortion at steam sterilizing temperatures of 121.degree. C. and the like. This, in turn, can cause the significant disadvantage that a luer type connection site may be spoiled by the warpage of dimensional distortion which can take place upon steam sterilization. A luer connector is a tapered hollow tubing which fits into a correspondingly sized socket of a luer adaptor, to provide a tight, aseptic seal. Many conventional administration sets utilize this type of connection.
As the result of this, manufacturers have been forced to sterilize many of the administration sets of polyvinyl chloride or other heat-distortable plastics with ethylene-oxide or, alternatively, some other low heat technique such as radiation sterilization, since the desirable and inexpensive luer adaptor connection site has not been successfully maintained in its proper dimensions for effective sealing under steam sterilization.
In accordance with this invention, the dimensional integrity of an end of thermoplastic tubing may be maintained at temperatures which are capable of causing dimensional distortion of the tubing end. As a result of this, commercial medical administration sets may be steam-sterilized in such circumstances where that it is desirable, without compromising the quality of luer adaptor sites on the sets, which otherwise could be warped by the temperatures encountered in the steam sterilization process. This opens up further significant economies in the mass production of medical administration and other sets to reduce the cost of their manufacture, while maintaining high reliability for aseptic connection with other units.